Simple GUI MD5/SHA256/SHA1 Hashsum Checker and Generator

checker.py

import hashlib
from tkinter import *
from tkinter.filedialog import askopenfilename


class App:
    BLOCK_SIZE = 4096

    # Initialize the application window
    def __init__(self, master):
        frame = Frame(master)
        frame.grid()

        # Row 1
        Label(master, text="File:").grid(row=0, sticky=W, padx=5)
        self.file_input = Entry(master, width=43)
        self.file_input.grid(row=0, column=1, padx=5, pady=5)

        file_select = Button(master, text="...",
                             command=self.select_file, relief=GROOVE)
        file_select.grid(row=0, column=2, padx=5, sticky=W)

        # Row 2
        Label(master, text="Sum:").grid(row=1, sticky=W, padx=5)
        self.hashsum = Entry(master, width=43)
        self.hashsum.grid(row=1, column=1, sticky=W, padx=5, pady=5)

        self.hashsum_pf = StringVar()
        hashsum_pf_label = Label(master, textvariable=self.hashsum_pf)
        hashsum_pf_label.grid(row=1, column=2)

        # Row 3
        Label(master, text="Type:").grid(row=2, padx=5)

        self.enc_type = StringVar(master)
        self.enc_type.set("MD5")

        enc_dropdown = OptionMenu(master, self.enc_type, "MD5", "SHA256", "SHA1")
        enc_dropdown.grid(row=2, column=1, pady=5, sticky=W)
        enc_dropdown.config(relief=GROOVE)

        Button(master, text="Go", relief=GROOVE, command=self.check_hash).grid(
            row=2, column=2, pady=5, sticky=W)

    # Present the user with a file choosing dialog
    def select_file(self):
        file_path = askopenfilename()
        # Update the file path field
        self.file_input.delete(0, END)
        self.file_input.insert(0, file_path)

    # Generate the checksum for the specified file and check if it matches the one provided
    def check_hash(self):
        # Map dropdown values to their respective hashing functions
        func_map = {
            "MD5": hashlib.md5,
            "SHA256": hashlib.sha256,
            "SHA1": hashlib.sha1
        }
        # Select the proper hashing function
        hasher = func_map[self.enc_type.get()]()

        # Read in the file in blocks instead of trying to process it all at once
        with open(self.file_input.get(), "rb") as f:
            for chunk in iter(lambda: f.read(self.BLOCK_SIZE), b""):
                hasher.update(chunk)

        # Did the user insert a hashsum to check?
        if len(self.hashsum.get()) > 0:
            # Compare the generated hashsum to the provided one
            if hasher.hexdigest() == self.hashsum.get().lower():
                self.hashsum_pf.set("P")
            else:
                self.hashsum_pf.set("F")
        else:
            # Update the hashsum field with the generated sum
            self.hashsum.insert(0, hasher.hexdigest())
            self.hashsum_pf.set("")


master = Tk()
master.title("Checksum Tool")
master.geometry("350x100")
master.resizable(0, 0)
app = App(master)
master.mainloop()